Microfluidic dose–response platform to track the dynamics of drug response in single mycobacterial cells

Abstract

Preclinical analysis of drug efficacy is critical for drug development. However, conventional bulk-cell assays statically assess the mean population behavior, lacking resolution on drug-escaping cells. Inaccurate estimation of efficacy can lead to overestimation of compounds, whose efficacy will not be confirmed in the clinic, or lead to rejection of valuable candidates. Time-lapse microfluidic microscopy is a powerful approach to characterize drugs at high spatiotemporal resolution, but hard to apply on a large scale. Here we report the development of a microfluidic platform based on a pneumatic operating principle, which is scalable and compatible with long-term live-cell imaging and with simultaneous analysis of different drug concentrations. We tested the platform with mycobacterial cells, including the tubercular pathogen, providing the first proof of concept of a single-cell dose–response assay. This dynamic in-vitro model will prove useful to probe the fate of drug-stressed cells, providing improved predictions of drug efficacy in the clinic.

Breaking the clean room barrier: exploring low-cost alternatives for microfluidic devices

“…Labs-on-a-chip (LOCs) devices have been made possible by microfluidic technology, which enables the miniaturization and optimization of processes. The industry has been focusing on their development ( Mistretta et al, 2022 ; Najjar et al, 2022 ). However, traditional techniques for producing LOCs are expensive, limiting their availability and creating a need for more efficient and cost-effective alternatives ( Ren et al, 2013 ; Elvira et al, 2022 ).…”

“…However, traditional techniques for producing LOCs are expensive, limiting their availability and creating a need for more efficient and cost-effective alternatives ( Ren et al, 2013 ; Elvira et al, 2022 ). Consequently, several low-cost microfluidic device manufacturing techniques have emerged to replace traditional manufacturing techniques requiring clean room facilities ( Leung et al, 2022 ; Mistretta et al, 2022 ).…”

“…Polydimethylsiloxane (PDMS) is the most commonly used elastomer due to its compatibility with biological samples, optical clarity, and ease of fabrication for valves and pumps ( de Almeida Monteiro Melo Ferraz et al, 2020 ; Dabaghi et al, 2021 ; Yandrapalli et al, 2021 ; Crevillen et al, 2022 ; Mistretta et al, 2022 ; Natsuhara et al, 2022 ). However, one of the major drawbacks of PDMS is its tendency to swell in the presence of certain solvents, particularly hydrocarbons, which can causee device failure ( Raj & Chakraborty, 2020 ; Miranda et al, 2021 ).…”

Dynamic microfluidic single-cell screening identifies pheno-tuning compounds to potentiate tuberculosis therapy

“…To implement the µDeSCRiPTor strategy, we first had to construct a multi-condition microfluidic platform compatible with bacterial growth (Fig. 1a), starting from a scalable module we developed earlier 20 . This module is composed of two layers of polymethyl siloxane (PDMS) patterned with a 300µm-wide channel crossing a 1000µm-wide circular chamber.…”

“…Although digital microfluidics allows higher-throughput applications than continuous-flow microfluidics, encapsulation of small bacterial cells within hydrolipid droplets poses major limitations to both spatiotemporal resolution and environmental flexibility 19 . To overcome these drawbacks, we present here a customized multi-condition microfluidic platform, stemming from our scalable microfluidic cell-culture chamber 20 , which operates on gentle hydro-pneumatic trapping of cells and allows two-dimensional growth. In short, we combined thirty-two pairs of microchambers that not only share a common microfluidic network but are also supplied via independent reservoirs, to be able to inject a different solution into each microchamber.…”